HR: 0830h
AN: SH11C-1114    [PDF]
TI: Magnetic Effects at the Edge of the Solar System: MHD Instabilities, the {\it de Laval nozzle} effect and an Extended Jet
AU: * Opher, M
EM: merav.opher@jpl.nasa.gov
AF: Jet Propulsion Laboratory, 4800 Oak Grove Drive, Pasadena, CA 91109 United States
AU: Liewer, P
EM: paulett.liewer@jpl.nasa.gov
AF: Jet Propulsion Laboratory, 4800 Oak Grove Drive, Pasadena, CA 91109 United States
AU: Velli, M
EM: marco.velli@jpl.nasa.gov
AF: Jet Propulsion Laboratory, 4800 Oak Grove Drive, Pasadena, CA 91109 United States
AU: Velli, M
EM: marco.velli@jpl.nasa.gov
AF: Department of Astronomy and Space Science, Univ. of Florence, Firenzi, FL 50125 Italy
AU: Bettarini, L
EM: betta@arcetri.astro.it
AF: Department of Astronomy and Space Science, Univ. of Florence, Firenzi, FL 50125 Italy
AU: Gombosi, T I
EM: tamas@umich.edu
AF: Space Physics Research Laboratory, The University of Michigan, Ann Arbor, MI 48109 United States
AU: Manchester, W
EM: chipm@umich.edu
AF: Space Physics Research Laboratory, The University of Michigan, Ann Arbor, MI 48109 United States
AU: DeZeeuw, D L
EM: darrens@umich.edu
AF: Space Physics Research Laboratory, The University of Michigan, Ann Arbor, MI 48109 United States
AU: Toth, G
EM: gtoth@hermes.elte.hu
AF: Space Physics Research Laboratory, The University of Michigan, Ann Arbor, MI 48109 United States
AU: Sokolov, I
EM: igorsok@umich.edu
AF: Space Physics Research Laboratory, The University of Michigan, Ann Arbor, MI 48109 United States
AB: To model the interaction between the solar system and the interstellar wind magnetic fields, ionized and neutral components besides cosmic rays must be included. Recently (Opher et al. ApJL 2003) found, that by including the solar magnetic field in an high resolution run with the University of Michigan BATS-R-US code, a jet-sheet structure forms beyond the Termination Shock. Here we discuss the formation of the jet and its subsequent large period oscillation due to magnetohydrodynamic instabilities. We perform in a simplified two dimensional geometry resistive magnetohydrodynamic calculation of a plane fluid jet embedded in a neutral sheet with the profiles taken from our simulation. We find remarkable agreement with the full three dimensional evolution. We present an even higher resolution three dimensional case where the jet extends for $150AU$ beyond the Termination Shock. We compare the temporal evolution of the jet showing that the sinuous mode is the dominant mode that develops into a velocity-shear-instability with a growth rate of $5 \times 10^{-9} sec^{-1}=0.027 years^{-1}$. As a result the outer edge of the heliosphere presents remarkable dynamics, such as turbulence and flows caused by the motion of the jet. Further study, e.g., including neutrals and the tilt of the solar rotation from the magnetic axis, is required before we can definitively address how this outer boundary behaves. Already, however, we can say that the magnetic field effects are a major player in this region changing our previous notion of how the solar system ends.
DE: 7811 Discontinuities
DE: 7827 Kinetic and MHD theory
DE: 7843 Numerical simulation studies
DE: 7871 Waves and instabilities
SC: SPA - Solar and Heliospheric Physics [SH]
MN: 2003 Fall Meeting